This invention relates to a row crop harvester adapted to be mounted on the forward end of a combine or similar mechanized harvesting machine. More particularly, the invention relates to a row crop harvester with increased density of individual harvesting units on the structure to facilitate increased percentage of recovery of crop from down crops and the like, and, also to enable effective harvesting of closely-planted rows of crops.
Agricultural harvesting machines, such as combines, are fitted on their forward end with a variety of row crop harvesting devices or headers, such as a corn head. A typical row crop harvester, comprises a plurality of individual row harvesting units (row units) each separated by a plurality of row crop dividers. As the combine moves through a field planted with a row crop, adjacent crop dividers define areas into which the crop being harvested is drawn by a gathering structure associated with each of the individual row units. The gathering structures typically comprise gathering chains or serpentine gathering belts to urge the crop further into the individual row units where a cutting mechanism or snapping rollers separate the desirable portion of the crop from other portions of the plant. The harvested crop is urged rearward toward the combine by action of the combine moving forward through the crop and the motion of the gathering chains urging the crop rearwardly toward a laterally disposed auger, which further urges the crop toward the intake to the separator portion of the combine. Typical row crop header units are disclosed in U.S. Pat. Nos. 3,808,783 and 3,759,021, each of which is incorporated herein by reference. A variety of row crop dividers also exist, such as those disclosed in U.S. Pat. No. 5,195,309, which is incorporated herein by reference.
For discussion purposes, features of the corn head will be examined, although it will be apparent that features of this invention are applicable to other crops. Individual corn collecting units (referred to herein as row units or harvesting units), such as those in a 40 Series John Deere corn head, typically comprise a pair of gathering chains, each chain disposed around a rearward chain gear drive and a forward idler chain gear. The chains extend forwardly from the platform of the combine and are configured in the same plane to form generally parallel lines of chains arranged to urge cornstalks rearwardly into the header. Located immediately below the gathering chains is a pair of snap rollers, configured to pull corn plants downwardly between the rollers so as to separate corn ears from the corn stalks. The individual row units are mounted to the frame of the header and typically are driven from a common power shaft that extends parallel to the header auger. Historically, harvesting units have been set up to be, within certain limits, adjustable so that the individual row units can be located to take best advantage of the crop row placement in the field. Generally, the row units are arranged so that each row unit is dedicated to each row of crop. In the past, typically the corn crop row spacing has been kept at nominally 30 inches between rows. This allowed for pest and weed control and provided optimal growing conditions for the cultivars available.
More recent developments in seed technology, fertilizer availabilities, pest and weed control are allowing corn crops to be planted in narrower rows to make better use of the available farmland. These rows have become as narrow as 15 inches. Traditional corn harvesting equipment cannot generally be adjusted to accommodate these narrower rows, however. The typical problem involved is that the return side of the gathering chains of adjacent individual row units interfere with each other when the units are placed in close proximity, generally preventing placement significantly closer than 30 inch spacing.
In addition, the close spacing of individual row units facilitates lifting and retrieval of downed crops. Generally, corn and similar crops are allowed to dry for a period of time in the fields prior to harvesting to minimize crop damage due to spoilage and the need for mechanical drying. However, late season storms can topple portions of the crop creating what is called a "downed crop" condition. In this instance, the individual stalks of corn are lying across the rows and entangled with one another. Further, the stalk can be essentially lying on the ground. A typical wide row harvester approaching a downed crop has a tendency to lift portions of the downed crop with the stalk upside down in an inverted U-shape such that, when pulled into the widely spaced crop gathering units, the ears of the plant pass below the snap rollers and are forced down with the rejected silage, thus reducing an ultimate crop yield. Narrower spacing of the individual crop units tends to lift the downed crop in a configuration which is less likely to reject useful ears of corn. Further, the narrow spacing ensures more structures for picking the corn ears so that the random nature of the downed crop can be more easily dealt with.